Search for: All records

Here we report on the direct measurement of the resonance strengths of the $E_{\mathrm{R}}^{\mathrm{lab}}=647\mathrm{keV}$and 1842 keV resonances in the ${}^{40}\mathrm{Ca}(p,\gamma ){}^{41}\mathrm{Sc}$reaction. At novae temperatures, $0.2<T_9<0.7$, the ${}^{40}\mathrm{Ca}(p,\gamma ){}^{41}\mathrm{Sc}$reaction is governed by the low energy resonance at $E_{\mathrm{R}}^{\mathrm{lab}}=647\mathrm{keV}$, whereas the $E_{\mathrm{R}}^{\mathrm{lab}}=1842\mathrm{keV}$resonance serves as a normalization standard for nuclear reaction experiments within the astrophysically relevant energy range. For the $E_{\mathrm{R}}^{\mathrm{lab}}=647\mathrm{keV}$resonance, we obtain a resonance strength $\omega \gamma =(2.51\pm 0.{09}_{\mathrm{stat}}\pm 0.{22}_{\mathrm{syst}})\mathrm{meV}$, with an uncertainty a factor of 2.5 smaller than the previous direct measurement value. For the $E_{\mathrm{R}}^{\mathrm{lab}}=1842\mathrm{keV}$resonance, we obtain a resonance strength $\omega \gamma =(0.148\pm 0.{006}_{\mathrm{stat}}\pm 0.{013}_{\mathrm{syst}})\mathrm{eV}$, which is consistent with previous studies but deviates by $2\sigma$from the most recent measurement. Our results suggest ${}^{40}\mathrm{Ca}$to be a strong waiting point in the nucleosynthesis path of oxygen-neon (ONe) novae. Published by the American Physical Society2025 

In this work, we report the measurement of elastic and Coulomb break-up channels in⁶He+²⁰⁸Pb collisions at E_lab= 19.3 MeV, close to the Coulomb barrier of this system ∼ 19 MeV. In the context of the astrophysical r-process, the reaction⁴He(2n,γ)⁶He has been proposed to be a key reaction in the path of synthesizing seed nuclei for the r-process, as¹²C, in an environment composed mainly of alpha particles and neutrons. Based on a theoretical approach for treating three body reactions by means of which its reaction rate can be inferred, our experimental approach aims to obtain an indirect measurement of the reaction rate of⁴He(2n,γ)⁶He by measuring the Coulomb breakup of⁶He under the intense electric field produced by a²⁰⁸Pb target nucleus. The experiment was carried out at the TriSol facility operated in the Nuclear Science Laboratory of the University of Notre Dame, USA, which delivered a⁶He beam together with other contaminants. Particular care must be taken for the alpha particles produced in the production reaction.